JP2004354267A - Printed matter measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed matter measuring device wherein the printed matter is constituted of a plurality of reference images, capable of comparing easily the color density between the printed matter and a reference paper even when the reference papers are prepared for each single reference image. <P>SOLUTION: In this printed matter measuring device, first of all, the first image data are acquired from a sampled printed matter in the step S2. Then, a plurality of reference papers are imaged integrally in the step S3. In the step S4, each reference image is extracted respectively from the acquired reference image data. In the step S5, the rotation angle of each reference image is corrected. In the step S6, the reference images are arranged corresponding to layout of the printed matter to acquire the second image data. In the step S7, the color densities of the first image data and the second image data are measured. In the step S8, comparison operation of the color densities is performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a printed matter measurement method for measuring the color density and the like of a printed matter from image data obtained by imaging the printed matter and comparing the measured color density with the color density measured from image data of a reference paper prepared in advance. Equipment related.
[0002]
[Prior art]
2. Description of the Related Art There is a printed matter measuring device that mounts a printed matter on a table, performs imaging, and measures a color density at an arbitrary position on the printed matter based on obtained image data. (See, for example, Patent Document 1)
[0003]
In such a printed matter measuring apparatus, printing is performed in accordance with the result of comparing the color density at a predetermined position of a printed matter extracted from a printing machine (hereinafter, referred to as a extracted printed matter) with the color density at a corresponding position of a previously prepared reference image. It controls the amount of ink supplied to the machine. As the reference image, for example, it is conceivable to use a reference print material prepared in advance (a print material or a print sample created by proof printing or the like; hereinafter, referred to as reference paper).
[0004]
Note that the measurement of the color density referred to in this specification is to convert the color of a printed matter into a numerical value using a predetermined color system. For example, a density value corresponding to each color such as YMCK or RGB, L ^* a ^* b ^* Means to find a numerical value in a known color system.
[0005]
[Patent Document 1]
JP-A-2001-353852 [0006]
[Problems to be solved by the invention]
The reference paper does not always have the same appearance as the sample printed matter. For example, in printing of a book or the like, a plurality of pages are printed in a state of being imposed, and bookbinding is performed by performing a predetermined folding process. Therefore, the extracted printed material is constituted by a printed material on which a plurality of pages are imposed. In addition, since the imposition is arranged according to the manner of folding the printing paper, so-called signatures, the imposition is not arranged in the page order, and the top and bottom of each page do not match.
[0007]
However, a proof print when a print sample is made is printed in units of pages due to limitations on the output size of the proofing device, or is printed in a combination of pages that are spread when actually bound. Sometimes. Alternatively, the client may hand a prepared print sample.
[0008]
If the appearance of the reference paper as the reference for color matching is different from the appearance of the actual printed matter, the size and arrangement of the two image data obtained by the printed matter measuring apparatus do not match. For this reason, there arises a problem that the corresponding position between the images cannot be obtained accurately. In this case, there is a possibility that the measurement positions for comparing the color densities are different, and the color tone of the printed matter cannot be accurately controlled.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a printed matter measuring apparatus capable of performing an accurate comparison even when the reference paper and the extracted printed matter have different formats.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, an image of a printed matter printed by a printing apparatus and a reference paper prepared in advance are captured to acquire respective image data, and a color density of the printed matter obtained based on each image data is compared. In a printed matter measuring device capable of managing the color tone of the printed matter by calculating, the printed matter is a printed matter constituted by a set of images of a plurality of reference papers, and a first obtained by imaging the printed matter. First storage means for storing image data, second storage means for storing reference image data obtained by collectively imaging a plurality of reference sheets on which the reference image is printed, and the second storage means Extracting means for extracting individual reference images from the reference image data stored in the means, and arranging and synthesizing the extracted reference images so as to correspond to the first image data to generate second image data Image synthesis A color density at a corresponding position of both image data from a column and a pixel value at a predetermined position of the first image data and a corresponding pixel value at a predetermined position of the second image data; And a color density measuring means capable of measuring the color density.
[0011]
The invention according to a second aspect is the printed matter measuring apparatus according to the first aspect, further comprising a rotation correction unit that performs a rotation correction on the reference image extracted by the extraction unit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of a printed matter measuring device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the printed matter measuring device.
[0013]
The printed matter measuring device 1 includes an imaging unit 3 that captures an image of a printed matter (sampled printed matter or reference paper) placed on a table 2, first and second storage units 4 that store image data obtained by the imaging unit, 5, operation control means 6 for performing an operation based on the image data, display means 7 for displaying the image data, designation means 8 for designating a position on the image on the display means 7, And a third storage means 9 for storing the same. The printed matter measuring device 1 is connected to the printing device 10 and the plate making device 11 so that data communication is possible.
[0014]
The table 2 is in the shape of a flat table on which printed matter can be placed, and is preferably provided with suction holding means and the like on the surface so that the printed matter can be supported smoothly.
[0015]
The imaging means 3 is composed of a two-dimensional CCD camera or the like mounted on the table 2, captures an image of a printed matter or the like on the table 2 illuminated by light source means (not shown), and generates image data by photoelectric conversion.
[0016]
Image data obtained by the imaging unit 3 is stored in the first storage unit 4 or the second storage unit 5. In this embodiment, each of the first and second storage means 4 and 5 is constituted by a memory means comprising a RAM, and the first storage means 4 is provided in the first storage means 4 for easy understanding. Image data (hereinafter, referred to as first image data) of a printed matter is stored, and image data (hereinafter, referred to as reference image data) of a plurality of reference sheets prepared in advance are stored in the second storage unit 5. Shall be stored. Of course, the first image data and the reference image data may be stored in different storage areas of the same memory means in parallel as an apparatus configuration.
[0017]
The present invention is characterized in that a plurality of reference sheets are collectively imaged on a table to obtain reference image data.
[0018]
The arithmetic control means 6 extracts each reference image from the reference image data recorded in the second recording means 5 and arranges the reference images in a desired arrangement to generate second image data. A color density at an arbitrary position on a corresponding image is calculated from the second image data and the first image data stored in the first storage means 4, and the device configuration has an arithmetic processing function. It comprises a microcomputer. The arithmetic control means 6 functions as an extracting means, a rotation correcting means, an image synthesizing means, a color density calculating means and the like in the present invention according to the processing operation of the program.
[0019]
The display unit 7 includes a CRT or a liquid crystal panel capable of displaying image data, and can display the first image data, the reference image data, and the like. The designating means 8 is composed of a known mouse or keyboard, and can designate a position with respect to the reference image data displayed on the display means 7. The display means 7 and the designation means 8 may be integrated by adopting, for example, a liquid crystal display means having a touch panel function.
[0020]
The third storage unit 9 is configured by a RAM memory or the like, like the first and second storage units 4 and 5, and is used when storing measurement results, generated second image data, and the like. . As described above, the third storage means 9 may be constituted by the same memory means as the first and second storage means.
[0021]
The printing device 10 is a printing device that prints the above-described sampled printed material, and corresponds to, for example, an offset printing device that can adjust the print density for each color of YMCK. Such a known offset printing apparatus includes an ink amount adjusting mechanism such as an ink fountain device. The printed matter measuring apparatus 1 according to this embodiment compares the first image data of the extracted printed matter with the second image data obtained by synthesizing the reference image of the reference paper, and compares the comparison result or the comparison result. Is transmitted to the printing apparatus 10, and the color adjustment in the printing apparatus 10 is performed according to the adjustment amount.
[0022]
The plate making device 11 is, for example, a device that creates a printing plate used by the printing device 10. From the plate making device 11, an image on a printing plate, that is, image data in which a reference image is arranged in the same manner as a sample print can be taken. As such image data, for example, PPF data in the CIP3 standard can be used. The printing device 10 and the plate making device 10 may be a printing device with a plate making mechanism that integrates both functions.
[0023]
Next, the operation procedure of the printed matter measuring apparatus 1 according to the present invention will be described with reference to the flowchart of FIG. FIG. 3 is an explanatory diagram showing an example of each image of the reference paper and the extracted printed material, which will be referred to in the following description as needed.
[0024]
2, first, in step S1, PPF data representing an image on a printing plate is received from the plate making apparatus 11 in advance. In the present embodiment, the PPF data is used as a reference for adjusting the arrangement of the reference image to the printed matter. In the following description, FIG. 3A shows the PPF image data G1.
[0025]
In the next step S2, the printed matter is imaged by the printed matter measuring device 1 and the obtained image data G2 is stored in the first storage means 4 as first image data. The image data of the extracted printed matter has the same arrangement as that of FIG. Note that the order of the step S2 may be changed to the following steps S3 to S6 (not shown).
[0026]
In the next step S3, an image of the reference paper is taken by the printed matter measuring apparatus 1, and the reference image data G3 is stored in the second storage means 5. In this imaging, imaging is performed collectively with a plurality of reference papers arranged on the table 2 so as not to overlap. For example, FIG. 3B is an example of the reference image data obtained by collectively imaging a plurality of reference sheets as described above, and the arrangement positions of the reference images G4 and G5 are appropriate. As described above, by collectively imaging the reference paper, the operation procedure (the number of times of imaging) by the operator can be reduced.
[0027]
In step S4, each reference image G4, G5 is extracted from the reference image data G3 obtained by imaging the reference paper. As an example, the paper edges P1 to P6 of the respective reference images G4 and G5 are specified on the reference image data G3 by the specifying means 8 such as a mouse. Note that in this example, three points on each of the paper edges located on the diagonal of each of the reference images G4 and G5 are specified. The image data of the reference images G4 and G5 thus extracted is temporarily stored, for example, in the third storage unit 9 or the like.
[0028]
In step S5, the obtained reference images G4 and G5 are corrected to an appropriate rotation angle with reference to the PPF image G1. For example, the angle is corrected so that the line segment connecting the paper edges P2 and P3 is in the same direction as the image on the PPF data G1 (in this case, the horizontal direction). Then, the image data of the reference image that has been rotationally corrected in step S5 is temporarily corrected in the third storage unit 9 or the like.
[0029]
Which paper edge of the reference images G4 and G5 should be aligned with which direction on the PPF data may be instructed by the operator each time, or may be set in advance by using condition data. For example, the designated points P7 to P10 may be designated on the PPF data, and the rotation correction may be performed so that the paper ends P1, P3, P4, and P6 respectively match the designated points.
[0030]
Next, in step S6, the reference images subjected to the rotation correction are arranged and combined based on the PPF data. For example, two feature points Q1 to Q2 and Q3 to Q4 are designated on the reference images G4 and G5, respectively. As the characteristic points Q1 to Q4, for example, points that are easily distinguishable on the picture (corner of the picture, etc.) are selected. On the other hand, feature points Q5 to Q8 at the same positions corresponding to the feature points Q1 to Q4 are designated on the PPF data G1.
[0031]
In accordance with the designation of the feature points Q1 to Q8, the arithmetic and control unit 6 arranges and combines the reference images G4 and G5. That is, each pixel data of the reference image G4 is coordinate-transformed and arranged so that the feature points Q1 and Q2 match the feature points Q5 and Q6. Similarly, each pixel data of the reference image G5 is coordinate-transformed and arranged so that the feature points Q3 to Q4 match the feature points Q7 to Q8. In this coordinate conversion, the image size is also enlarged or reduced. Thus, image data G6 (second image data in the present invention, not shown) in which the reference images G4 and G5 are arranged in the same layout as the PPF data G1 is generated. The second image data G6 is stored again in, for example, the second storage unit 5.
[0032]
In step S7, the color density of the first image data G2 and the second image data G6 is measured. This measurement is performed, for example, on a representative color point (for example, a color point considered important on a picture) when performing color control set for each ink key of the printing press in advance.
[0033]
In step S8, the color densities measured for the first image data G2 and the second image data G6 are compared. Then, an adjustment value for adjusting the ink supply amount is calculated based on the difference or deviation of the color density, and transmitted to the printing apparatus 10.
[0034]
According to the above flow, there is an advantage that the number of times of imaging can be reduced by imaging the reference paper collectively. Then, the image data arranged in the same manner as the printed matter can be synthesized by a simple operation using the reference image data taken collectively.
[0035]
[Other embodiments]
In the above-described embodiment, the reference paper is placed on the table so as not to overlap as appropriate, and collective imaging is performed, and then the rotation of the extracted reference image is corrected. However, the step of correcting the rotation of the reference image may be omitted if the apparatus is placed on the table so as to regulate the rotation angle using, for example, a guide.
[0036]
In the above embodiment, the reference image is arranged based on the PPF data. However, the reference image may be arranged based on the first image data obtained from the imaging of the sampling print. In the case of printing a page such as a book, each reference image may be automatically arranged based on page layout data used in the plate making apparatus. Also, the extraction and rotation correction of the reference image may be automatically processed using image processing techniques such as contour extraction and pattern matching.
[0037]
【The invention's effect】
According to the present invention, the reference image data is obtained by collectively imaging a plurality of reference papers, so that the number of times of imaging can be reduced.
[0038]
According to the second aspect of the present invention, since a means for correcting the rotation of the extracted reference image is provided, when a plurality of reference sheets are collectively imaged, they can be roughly arranged and imaged without concern for the angle of each reference sheet. Work efficiency is good.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a printed matter measuring device according to the present invention.
FIG. 2 is a flowchart showing an operation procedure in the printed matter measuring device.
FIG. 3 is an explanatory diagram illustrating an arrangement of a reference image.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 printed matter measuring device 3 imaging means 4 first storage means 5 second storage means 6 arithmetic control means 7 display means 8 designation means 9 third storage means 10 printing device 11 plate making device

Claims (2)

The color tone of the printed matter is managed by capturing the image data of the printed matter printed by the printing apparatus and the reference paper prepared in advance, acquiring the respective image data, and comparing and calculating the color density of the printed matter obtained based on each image data. In a printed matter measuring device capable of
The printed matter is a printed matter constituted by a set of images of a plurality of reference paper,
First storage means for storing first image data obtained by imaging the printed matter;
A second storage unit that stores reference image data obtained by collectively imaging a plurality of reference sheets on which the reference image is printed,
Extracting means for extracting individual reference images from the reference image data stored in the second storage means;
Image synthesizing means for arranging and synthesizing the extracted reference image so as to correspond to the first image data to generate second image data;
A color density at a corresponding position of both image data is measured from a pixel value at a predetermined position of the first image data and a corresponding pixel value at a predetermined position of the second image data. And a color density measurement unit capable of performing the measurement. The apparatus according to claim 1, further comprising a rotation correction unit configured to perform rotation correction on the reference image extracted by the extraction unit.

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